[20.02] Star-formation at z=2.4 from a sample of Lyman \alpha emitters

We have carried out a search of Lyman \alpha candidates
over a field of 1200 \sq ' using the CFH12K camera at the
CFHT and a custom medium band filter. The search has
unconvered 155 candidates, corresponding to a density of
~0.13 \sq ' -1. We find that our sources have
very red colors which imply either that a large fraction of
the light is reddened and we are detecting Lyman \alpha
through special lines of sight or that the objects contain
an underlying older stellar population. While for each
individual objects we cannot discriminate between these
models, we expect that most of the objects will actually
contain an older components since the star formation rate
inferred from the model with reddening would exceed by a
large factor the peak star formation rate as measured by
Madau et al. and Steidel et al. Thus it appears that typical
Lyman \alpha emitters at z=2.4 experienced their major
episode of star formation at higher redshift.